This invention relates to a process for producing a preservative having anti-oxidant and anti-bacterial action. The preservative may be suitably added to oily and fatty foods, oil and fat containing foods, other foods, cosmetics, medicines and the like.
Herb family spices are known to be an effective anti-oxidant to oils and fats and oily and fatty foods. Researches have been made on this subject with a number of reports. Because of their own strong flavor, these spices or essential oils thereof may be directly added to foods for anti-oxidant action only to a limited extent within which the taste of the foods is not significantly changed. Furthermore, such spices will probably disproportion flavor balance when incorporated into cosmetics, or give rise to an undesired problem due to their own flavor when formulated into medicines.
It is therefore desired to recover a flavorless anti-oxidant fraction from such spices by removing flavoring components. For example, U.S. Pat. No. 3,950,266 discloses a process of preparing an anti-oxidant substance. According to the teachings of this U.S. Patent, powdered rosemary or sage is subjected to extraction with a low boiling solvent such as ethyl ether, and the solvent is distilled off from the resulting extractive to leave a crude product. The crude porduct is washed several times with cold water and then several times with hot water at 80.degree. C., dissolved in a solvent such as methanol, and then treated with activated carbon before the solvent is distilled off from the solution to obtain a refined product (which still has some flavor). Furthermore, the thus obtained product is dissolved in oil and the solution is steam distilled to remove the flavoring components, obtaining a flavorless anti-oxidant substance.
Another extraction process is disclosed in Japanese Patent Application Laid-Open No. 55-18435 in which rosemary or sage is subjected to extraction with 40-60% alcohol in water, water and activated carbon are added to the extractive, and then the solution is separated into a filtrate and a precipitate by filtration. Anti-oxidant fractions are obtained from the filtrate and the precipitate, respectively.
In addition to such typical processes for the extraction treatment of spices using polar solvents, also known are extraction processes using non-polar solvents or oils.
However, the inventors have carried out experiments and found that the extraction treatment of herb family spices such as rosemary and sage with a polar solvent such as ethanol results in an extractive which is inevitably contaminated with bitter components and hence, is somewhat unfavorable in taste. The use of a non-polar solvent such as n-hexane fails to fully extract an anti-oxidant fraction out of the starting spice, resulting in low yields. An extractive containing a high concentration of anti-oxidant components cannot be obtained by the extraction with oils.
It is also recognized that the herb family spices have anti-bacterial action. Relatively large amounts of spices must be added to provide the necessary anti-bacterial action, but the use of such spices in usual ground form will give rise to undesired problems including too strong flavor as discussed above. It is believed that the anti-bacterial action is generally attributable to essential oils. For example, eugenol is known as an anti-bacterial agent and is recovered from the essential oils of spices such as clove and allspice.